摘要：建立了一种析出模型用来模拟硼在硅中的扩散现象，描述了硼原子与离子注入引起的rp缺陷之间的相互作用，解释了非活性硼峰形成的原因，与实验结果能够较好的吻合，为研究硼的扩散机理提供了很好的依据，为超浅结工艺模拟提供了基本模型，对于开发下一代集成电路研制的工艺模拟程序有着非常重要的意义。
关键词：rp缺陷；硼峰；聚集析出；增速扩散 1 introduction boron diffusion after ion implantation is an active topic of resear-ch.however,many details concerning the interactions between boron atoms and ion implantation damage are still not understood.an interesting observation is that for boron implantation to medium doses,the peak portion of the boron profile is not electrically activated and has remained immobile during annealing for a long time,though the peak concentration is lower than the boron solubility in silicon.several models have been proposed to explain this result.according to the fermi-level model,boron diffuses mainly via positively charged si interstitials once its concentration exceeds the intrinsic carrier concentration.the diffusion via positively charged si interstitials is assumed to be much slower than that via neutral si interstitials[1].in the clustering model,the immobile boron peak is associated with the formation of electrically inactive boron interstitials clusters[2].in this work,we attribute the limited activation and mobility of the dopant to be the segregation on the extended defects[3,4]and present a model in which the immmobile boron peak is explained with boron segregation to rp defects. 2 experiment ion implantation produces extended defects or dislocation loops such as rp (the projected range) defects,eor and clamshell defects upon anneal-ing,depending on the dose and species[5].rp defects form during annealing at a depth corresponding approximately to rp when the dose exceeds the critical value of 1×1014cm-2 and simultaneously no amorphous layer is formed.[4]to produce rp defects,boron was implanted into n-type si wafers at 15 kev and 30kev with a dose of 2×1014cm-2 at 800℃.fig.1 shows the immobile boron peak dissolves with increasing annealing time.the depth range of hump of the boron concentration peak was found to be in the same depth range of rp defects.rapid diffusion occurs at low concentrations compared to the diffusion found at higher concentrations.the transition between these two regimes occurs at a concentration which is typically ten times lower that the b solubility limit.the boron solubility at 800 ℃ is around 4×1019cm-3[6]. 3 segregation model for boron pile-up the model implemented in this work uses kinetic reactions that lead to the segregation of boron.because of the difference of potential energy between boron atoms in the matrix and those at the periphery of rp defects,boron segregates to rp defects.the segregated boron atoms are released from rp defects at a rate determined by the hopping frequency of boron atoms and the boron segregation energy.the change of concentration of the boron atoms segregated to rp defects with time is given by the difference between the segregation rate and the release rate,that is
here crp represents the concentration of interstitials contained in rp defects.fig.2 indicates the immobile boron amount decreases exponentially with a char
安娜，夏建新 | （电子科技大学微电子与固体电子学院，四川 成都 610054） |
摘要：建立了一种析出模型用来模拟硼在硅中的扩散现象，描述了硼原子与离子注入引起的rp缺陷之间的相互作用，解释了非活性硼峰形成的原因，与实验结果能够较好的吻合，为研究硼的扩散机理提供了很好的依据，为超浅结工艺模拟提供了基本模型，对于开发下一代集成电路研制的工艺模拟程序有着非常重要的意义。
关键词：rp缺陷；硼峰；聚集析出；增速扩散 1 introduction boron diffusion after ion implantation is an active topic of resear-ch.however,many details concerning the interactions between boron atoms and ion implantation damage are still not understood.an interesting observation is that for boron implantation to medium doses,the peak portion of the boron profile is not electrically activated and has remained immobile during annealing for a long time,though the peak concentration is lower than the boron solubility in silicon.several models have been proposed to explain this result.according to the fermi-level model,boron diffuses mainly via positively charged si interstitials once its concentration exceeds the intrinsic carrier concentration.the diffusion via positively charged si interstitials is assumed to be much slower than that via neutral si interstitials[1].in the clustering model,the immobile boron peak is associated with the formation of electrically inactive boron interstitials clusters[2].in this work,we attribute the limited activation and mobility of the dopant to be the segregation on the extended defects[3,4]and present a model in which the immmobile boron peak is explained with boron segregation to rp defects. 2 experiment ion implantation produces extended defects or dislocation loops such as rp (the projected range) defects,eor and clamshell defects upon anneal-ing,depending on the dose and species[5].rp defects form during annealing at a depth corresponding approximately to rp when the dose exceeds the critical value of 1×1014cm-2 and simultaneously no amorphous layer is formed.[4]to produce rp defects,boron was implanted into n-type si wafers at 15 kev and 30kev with a dose of 2×1014cm-2 at 800℃.fig.1 shows the immobile boron peak dissolves with increasing annealing time.the depth range of hump of the boron concentration peak was found to be in the same depth range of rp defects.rapid diffusion occurs at low concentrations compared to the diffusion found at higher concentrations.the transition between these two regimes occurs at a concentration which is typically ten times lower that the b solubility limit.the boron solubility at 800 ℃ is around 4×1019cm-3[6]. 3 segregation model for boron pile-up the model implemented in this work uses kinetic reactions that lead to the segregation of boron.because of the difference of potential energy between boron atoms in the matrix and those at the periphery of rp defects,boron segregates to rp defects.the segregated boron atoms are released from rp defects at a rate determined by the hopping frequency of boron atoms and the boron segregation energy.the change of concentration of the boron atoms segregated to rp defects with time is given by the difference between the segregation rate and the release rate,that is
here crp represents the concentration of interstitials contained in rp defects.fig.2 indicates the immobile boron amount decreases exponentially with a char
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